Cyclic Vomiting Syndrome (CVS) (cont.)
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What other features and conditions accompany cyclic vomiting syndrome?
Most people with cyclic vomiting syndrome have normal intelligence, although some affected people have experienced developmental delay or intellectual disability, muscle weakness (myopathy), and/or seizures. People with these additional features are said to have cyclic vomiting syndrome plus.
How common is cyclic vomiting syndrome?
The exact prevalence of cyclic vomiting syndrome is unknown; estimates range from 4 to 2,000 per 100,000 children. The condition is diagnosed less commonly in adults, although recent studies suggest that the condition could be as common in adults as in children.
What are the genetic changes related to cyclic vomiting syndrome?
Although the exact causes of cyclic vomiting syndrome have yet to be determined, researchers have proposed several factors that may contribute to the disorder. These factors include changes in brain function, hormonal abnormalities, and gastrointestinal problems. Many researchers believe that cyclic vomiting syndrome is a migraine-like condition, which suggests that it is related to changes in signaling between nerve cells (neurons) in certain areas of the brain.
Some cases of cyclic vomiting syndrome may be related to genetic changes in mitochondrial DNA. Mitochondria are structures within cells that convert the energy from food into a form that cells can use. Although most DNA is packaged in chromosomes within the nucleus, mitochondria also have a small amount of their own DNA (known as mitochondrial DNA or mtDNA).
Several changes in mitochondrial DNA have been associated with cyclic vomiting syndrome. Some of these changes alter single DNA building blocks (nucleotides), whereas others rearrange larger segments of mitochondrial DNA. These changes likely impair the ability of mitochondria to produce energy. Defects in energy production may lead to symptoms during periods when the body requires more energy, such as when the immune system is fighting an infection. However, it remains unclear how changes in mitochondrial function are related to recurrent episodes of nausea and vomiting.